Objectives (1) To test the association between male rank and reproductive success in WRPRC's large social groups of Macaca mulatta; (2) to establish paternity with DNA profile tests, building the foundation for future multi-generation bilateral pedigree information for all individuals in these rhesus groups; (3) to assess differences between the two breeding groups in relative genetic diversity. ABSTRACT:Efforts to establish paternity in primates have been motivated by both the practical need for pedigree information in captive management, and by the importance of understanding primate social organization and behavior from a theoretical perspective. Knowledge of paternity would provide an invaluable dimension to the analysis of social affiliations, support networks, and male-infant interactions in primate groups, for example. Bilateral pedigree information is essential to our understanding of genetically transmitted disease proclivity in primates, and in tracing factors involved in reproductive failure. General availability of such information could signficantly enhance the selective criteria employed for subjects in a wide range of biomedical and other research protocols. Previous efforts (early 1980s) at this institute to establish paternity based on genetic markers alone were not sufficiently conclusive. Other rhesus populations have been analyzed to test paternity using a range of genetic markers and to a lesser extent, DNA fingerprinting, with highly variable results vis-a-vis the relationship between male rank and reproductive success. The large social groups of rhesus at the Vilas Ethology Laboratory are particularly valuable subjects for an examination of the relationship between male rank and reproductive success because (1) extremely detailed records have been maintained on group composition, births, deaths, stillbirths, and rank relationships for over 10 years, and (2) these groups have been managed for stability in the representation of matrilines. Extensive genealogical and historical analysis preparatory to genetic testing has been completed We will conduct DNA profile tests in collaboration with Drs. Casna and Gergits of Therion Corp., following successful collaboration in paternity analysis of stumptailed macaques. We will also assess differences between the two breeding groups in relative genetic diversity, using band-sharing coefficients from DNA tests as an index of relatedness. This study will provide further information on the strength of that technique. We will use the results of DNA profile tests and data on paternity to develop management strategies to maintain or enhance genetic diversity in these groups in future years. Key Words reproduction, paternity testing, minisatellite DNA, genetic transmission, genetic diversity